That's the question on homeowners' minds as house prices just posted their largest annual gain since 2005 -- congrats to those no longer "underwater" on their mortgages -- even as interest rates remain tantalizingly low. But here's the catch: Those same higher prices can make buyers as choosy as a Michelin restaurant reviewer.

"A house with a $1,600 mortgage payment last year now has a $2,000 mortgage payment," one broker told the Wall Street Journal. "Buyers are saying, 'I better like it.'"

To increase your home's "like" quotient, read on to see which upgrades are worth making and which aren't.

Worth It: A new front door. Strictly in terms of return on investment, a steel one topped the list of Remodeling magazine's annual Cost vs. Value Report for 2014 -- recouping 96.6 percent of the average price. But a fresh coat of paint can work wonders, too.

Not Worth It: A home-office remodel. We know what you're thinking: With so many more people working from home, wouldn't it be brilliant to rewire the space for electronic equipment, say, and install commercial-grade carpeting? Not really. The magazine gave it the lowest return on investment (48.9 percent), and the guy who oversaw the study says, "Home offices don't sell houses."

Worth It: A back-up power generator. It's the biggest gainer in the study, jumping 28 percent over last year, and plays especially well in areas brutalized by storms.

Not Worth It: Major bathroom work. "You could install the most spectacular jetted tub, and it still might not suit a buyer," says Patsy O'Neill, a sales associate with Sotheby's in Montclair, NJ. "Meanwhile, you'd have spent tens of thousands of dollars." That explains why it made Bankrate.com's list of "6 Worst Home Fixes for the Money" and why you should stick to things like re-grouting the shower.

Worth It: Roofing replacement. There's a reason this ultimate "curb appeal" enhancer consistently makes Remodeling's list and is up 11.2 percent over even last year: A roof is the first thing prospective buyers notice even before exiting their cars, and you can kiss that sale good-bye if yours looks like it's been through hell.

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